Question

For isothermal expansion of an ideal gas, the correct combination of the thermodynamic parameters will be:

• A. $\Delta U=0,Q=0,W\ne 0$ and $\Delta H\ne 0$
• B. $\Delta U\ne 0,Q\ne 0,W\ne 0$ and $\Delta H=0$
• C. $\Delta U=0,Q\ne 0,W=0$ and $\Delta \ne 0$
• D. $\Delta U=0,Q\ne 0,W\ne 0$ and $\Delta H=0$

Answer 1

The correct option is D $\Delta U=0,Q\ne 0,W\ne 0$ and $\Delta H=0$

For isothermal expansion of an ideal gas
$\Delta T=0$

$\therefore$ From $\Delta U=n{C}_v\Delta T$

$\Delta U=0$ and from

$\Delta H=n{C}_p\Delta T=0$

From first law of thermodynamics

$\Delta U=Q+W$

as $\Delta U=0\Rightarrow Q\ne 0$

and $W\ne 0$

$\therefore$ Parameters are

$\Delta U=0\Rightarrow Q\ne 0;W\ne 0and\Delta H=0$